﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Zad1
{
    public static class Extensions
    {
        public static StringBuilder Substring(this StringBuilder str, int index, int length)
        {
            string strToString = str.ToString();
            string result = strToString.Substring(index, length);
            return new StringBuilder(result);
        }
    }
    class Program
    {
        static void Main()
        {
            StringBuilder a = new StringBuilder("akldhauskdngasmdngasda");
            Console.WriteLine(a.Substring(3,5).ToString());
        }
    }
}
